The surfaces of substrates such as ships, underwater structures and fishing nets that are exposed to water for a long term easily undergo the adherence thereto of various aquatic creatures including animals such as oyster, mussel and barnacle, plants such as layer, and bacteria. The propagation of these aquatic creatures on the substrate surfaces would cause various problems: where the substrate is a ship, for example, the surface roughness increases from the waterline to the bottom of a ship, resulting in the decrease in the speed of a ship and increase in fuel cost of a ship. Where the substrate is a fishing net such as a culturing net and a fixed net, the clogging of the mesh by aquatic creatures could cause serious problems such as the death of cultured creatures and caught fish because of oxygen deficiency. Where the substrate is a water supply and exhaust pipe for seawater of e.g., a thermal power plant and a nuclear power plant, it may happen that the water supply and exhaust pipe for seawater (cooling water) is clogged or flow rate is decreased to disturb circulation systems.
Regarding such problems, in order to prevent the adherence of aquatic creatures onto various substrates, the research and development of antifouling paints to be applied on the substrates (antifouling coating composition) are underway.
As a conventional antifouling coating composition, a coating composition containing a hydrolyzable resin as a resin component (binder component) is known. As a typical example thereof, a coating composition containing a hydrolyzable resin having a triorganosilyl group has been developed. Such a coating composition is applied on the bottom of ships and the like in order to prevent aquatic creatures from adhering thereto.
The hydrolyzable resins having a triorganosilyl group that are generally known are the ones obtained by (co)polymerizing as a monomer component triisopropylsilyl acrylate (TIPSA) and/or triisopropylsilyl methacrylate (TIPSMA). For example, the following Patent Literatures 1 to 7 disclose antifouling coating compositions containing these (co)polymers.
Patent Literature 1 discloses a coating composition composed of a copolymer containing 55 to 75 parts by weight of tri-i-propylsilyl (meth)acrylate (a), 2 to 20 parts by weight of methoxyethyl acrylate (b) and 43 to 5 parts by weight of other polymerizable monomer (c), with respect to of 100 parts by weight of total monomer components, and an antifouling agent.
Patent Literature 2 discloses an antifouling coating composition containing, as a vehicle, a copolymer obtainable from a specific triorganosilyl methacrylate monomer, a specific alkoxyalkyl methacrylate monomer and an ethylenic unsaturated monomer copolymerizable with these monomers.
Patent Literature 3 discloses an antifouling coating composition containing a copolymer obtained from a specific triorganosilyl methacrylate monomer and a specific methoxyalkyl methacrylate monomer, and rosin copper salt or a rosin derivative copper salt.
Patent Literature 4 discloses a coating composition containing, as essential components, a copolymer obtained from silyl-based monomer having an acryloyloxy group and a specific monomer, and an antifouling agent.
Patent Literature 5 discloses a coating composition containing, as essential components, a rosin-based compound, an organosilyl ester group-having polymer obtained from a silyl-based monomer having acryloyloxy group and the like, and an antifouling agent.
Patent Literature 6 discloses an antifouling coating composition containing a triisopropylsilyl (meth)acrylate copolymer obtainable by copolymerizing triisopropylsilyl (meth)acrylate, methyl methacrylate and another (meth)acrylic acid ester and having a specific glass transition temperature and a specific number average molecular weight; a rosin copper salt or a rosin derivative copper salt; and cuprous oxide.
Patent Literature 7 discloses an antifouling coating composition containing a polymer obtained by polymerizing a polymerizable unsaturated carboxylic triorganosilyl and having a number average molecular weight of 1000 to 20000, and a rosin zinc salt or a rosin derivative zinc salt.